Straight edge for use in combination with large drafting board



March 2, 1965 R. E. BLoDGETT E'rAl. 3,171,209

STRAIGHTEDGEFORUSEIncoMBImnoN WITHLARGEDRAFTINGBOARD Fi1edApri124, 1962 Y zsheets-sheetl NVU/70H5: E0 s. BLODGETT (M p ATTORNEY March 2, 1965 R. E. BLonGET-r ETAI. 3,171,209

STRAIGHT EDGE FOR USE IN COMBINATION WITH LARGE DRAFTING BOARD 2 Sheets-Sheet 2 Filed April 24, 1962 nn ww BB 4 5s. Af 0 t Mw E ml. W; m m B M w w ATTORNEY United States Patent O 3,171,209 STRAIGHT EDGE FOR USE IN COMBINATIN WITH LARGE DRAFTING BARD Richard E. Blodgett and Leo S. Blodgett, both of Holmesbrook Road, Basking Ridge, NJ. Filed Apr. 24, 1962, Ser. No. 189,909 3 Claims. (Cl. 33 80) This invention has reference to a straight edge of the type used in combination with large drafting board in general, and the object of the present invention is the provision of a straight edge of the type above referred to, which will be accurate, convenient in use and cheap to manufacture.

It is an improvement over the straight edge forming the subject matter of a co-pending patent application led July 12, 1961, Serial No. 123,539, now Patent No. 3,122,835 in the names of Richard E. Blodgett and Leo S. Blodgett.

In the straight edge covered in that co-pending application, a strip of plastic material is formed at each end thereof, with longitudinal bosses drilled for receiving cylindrically-shaped plunger members to which are secured yoke-shaped elements, each having a pair of roller members adapted to engage parallel guides forming parts of a layout board under the tension of springs fitted over the reduced end portions of the plungers, such reduced end portions being rotatably and slidably movable into similarly sized apertures formed in the bosses and screw threaded at their ends for receiving nuts serving as stops for their respective plunger, as when removing the straight edge from the layout board.

While the straight edge disclosed in the above mentioned co-pending application has proved entirely satisfactory in actual use, the accuracy required in the machining of parts comprised therein has been found to be too exacting as to warrant the manufacture of such straight edge in large quantity production.

The novel features of the straight edge of the present invention will appear from the following description and by the claims appended thereto, reference being had to K FIG. 3 is an underside View of the straight edge shown i in FIG. 1, with portions broken away;

FIG. 4 is a cross-sectional view taken on line 4 4 of FIG. 1, looking in the direction indicated by the arrows;

FIG. 5 is a cross-sectional view taken on line 5 5 of FIG. 1, looking in the direction indicated by the arrows; FIG. 6 is a cross-sectional View taken on line 6 6 of FIG. l, looking in the direction indicated by the arrows; FIG. 7 is a cross-sectional view taken on line 7 7 of FIG. 1, looking in the direction indicated by the arrows;

FIG. 8 is a partial view showing a roller assembly, enlarged, shown in section, taken on line 8 3 of FIG. 3; and FIG. 9 is a partial view, enlarged, of a spring tensioning arrangement embodied in the straight edge of the invention.

The straight edge of the present invention, as shown in FIG. 1 and in the moditiul form shown in FIG. 2, consists of a bar 19, constructed of a clear plastic material, formed with two parallel bevelled edges 11 and 12 and a pair of projections in the form of knobs 13 and 14 serving for moving the straight edge on a drawing board.

To one end of bar It) is formed a recess 1S provided for receiving a flat yoke-shaped member 16, of light density metallic material, clamped to the bar 16B by a plate 17 and a plurality of similar screws 18. The opposite 3,171,209 Patented Mar. 2, 1965 ICC end of bar 10 is formed with a recess 19 serving for receiving two metallic bars 2t) and 21, best seen in FIGS. 2 and 6, clamped in parallel relation to each other onto the plastic bar by a plate 22, FIGS. 1, 2 and 6, and a number of similar screws 23 threaded into the plastic bar. The adjacent or inner disposed sides of bars 20 and 21 forming races for steel balls 24, 24x and 25, 25x placed in the spaces formed by these bars and the longitudinal adjacent sides of a plunger 26 of rectangular cross-section, as best seen in FIGS. 2, 6 and 7, the metallic bar 20 being provided with two pairs of laterally extending stud members 27-28 and 30-31 serving for limiting the movement of their respective balls 24 and 24x, while the bar 21 is provided with two pairs of laterally extending studs 31x-32 and 33-34 serving as stops for limiting the movement of balls 25 and 25x, respectively, while the stud 33 co-operates with a stud 34x carried by plunger 26 to serve as a stop for limiting the sliding movement of the plunger against the tension of a spring 35 having one end hooked to a pin 36 carried by the plastic bar 10 and its other end secured as by soldering into a countersink hole formed in a nut 37, best seen in the enlarged view in FIG. 9, this nut being itted for sliding, but against rotary movement, into a slot 38 formed in the plunger 26 upon the turning movement of a screw 39 threaded into the nut 37, which thus serves for adjusting the tension of the spring 35.

As best seen in FIGS. 1, 2 and 6, the plunger 26, the balls 24-24x, 25-25x, the tension spring 35 and the bars 2t) and 21, are held collectively in assembled relation to each other by the plate 22 secured to the plastic bar 10 by the screws 23. The opposite end of plunger 26 is formed with a rectangularly-shaped portion 40 having two recesses 41 and 42, best seen in FIGS. 3 and 7, into which arm members 43 and 44 are tted and secured as by a plurality of screws 45 and 46, respectively, to form a yoke-shaped members 16x, to the free ends of which are mounted, as on pivots 49 and 50, FIGS. 3 and 8, similar roller members in the form of discs 48, each pivot having one of their ends formed with a flat head or disc portion 53 and their other ends having a reduced diameter fitted into respective apertures in the ends of arms 43 and 44 of the yokes 16-16x thus formed, the pivots, and thereby the rollers 47-47 and 48-43, being held vin assembled relation by similar screws 51 and 52, FIGS. 1 and 7, while lock-washers, as 53x and 54, are disposed between the arms of the yokes and the head of screws 51 and 52 for positively securing the pivots 49 and 50 to their respective yoke, anti-friction washers, as SS-SSX, being inserted between the rollers 47-47 and 48 4S and their respective yoke arm for free rotation of the rollers upon the movement of' the straight edge onto the drafting board.

To the enlarged portion of plunger 26, opposite its recessed side, is secured, as by screws 56, an upward extending lug member 57, FIGS. l, 2 and 3, co-operating with a lug member 57x formed with the plate 22, for assisting in manually moving the plunger 26 against the tension of spring 35, as when removing and/or placing the straight edge thus constructed in position for engaging the rollers 47 47 `and 48 48 carried by the yoke members 16-16x with -the guiding elements of a drafting board, as indicated in dots and dash lines in the modified straight edge shown in FIG. 2.

In the present straight edges construction the plastic bar 1d at diiferent points along its length, as shown in FIGS. 1 and 3, is formed with slots 58, 59 and 6i), each provided with a pair of coaxially disposed recesses, as 61-62, 63-64 and 65-66, for receiving, as by press-fit engagement, respective spindles, as 67, 68 and 69, serving for rotatably mounting cylindrically-shaped roller members as 70, 71 and 72, provided for supporting the straight edge a small distance from the surface of the drafting board so as to facilitate the movement of the straight edge thereover and thereby avoiding catching and the consequent damaging of the drawing paper on the drafting board, while the under-surface of the disc portion 53 of each pivot 49 and 50 are laid in a plane a few thousandths of an inch above the underside surface of the straight edge bar, thus avoiding the rubbing of such disc portions onto the drafting board.

In the modification of the straight edge of this invention, as shown in FIG. 2, the arms 73-'73 and 74-'74 forming the yoke members, are constructed of unequal length with reference to the straight edge so as to permit positioning the latter in close proximity to either of the opposite ends of the `drafting board, that is, the ends which are nearer or away from the operator, as for example as indicated in dots and dash lines in FIG. 2, by the simple turning of the straight edge 180 in a horizontal plane.

In actual use of the straight edge, constructed according to the present invention, it has been found that even with a relatively light spring tension acting on the plunger 26, and thereby on the yokes, causes the straight edge to take up an accurate right angle position with reference to the parallel guiding elements of the drafting board with which the rollers carried by the yokes are engaged, irrespective of the length of the straight edge, which, in the present construction, is of the order of 38 inches long.

What we claim is:

1. A straight edge comprising a bar having parallel bevelled edges, a yoke member, a clamping plate for securing said yoke member to said bar at one end thereof, a pair of roller members at each end of said yoke member, a plunger member, a pair of parallely disposed metallic bars mounted on the opposite end of said bar in axial relation therewith, meansV interposed between the adjacent sides of said metallic bars and said plunger member,

a yoke member secured to said plunger member, a pair g of roller members carried by the last mentioned yoke member, and another plate secured to the first mentioned bar cooperating with said metallic bars and said means for snugly guiding said plunger member upon its longitudinal axial movement in position for engaging the rst and second mentioned pair of rollers with elements forming parts of a drafting board.

-shaped member, a plate bridging said metallic bars, a plunger member disposed for reciprocating movement between said metallic bars, a yoke member carried by said plunger, Vroller members at the end of each arm forming the last mentioned yoke member, the adjacently disposed sides of said bars and the outer disposed sides of said plunger member forming ball bearing races, a plurality of balls interposed between the races formed by said plunger member and said bars for facilitating the reciprocating movement of said plunger member, said plunger member having an elongated slot at one end thereof, a stud engaging the plastic bar and extending perpendicularly therefrom into the slot formed in said plunger member, a nut disposed in the slot formed in said plunger member, a screw loosely iitted at one end of said plunger member and threading into said nut, and a tension spring connecting with said nut and said plunger member for urging the rollers carried by each of said yoke members in Contact with parallelly disposed elements of the drafting board, and thereby guiding the straight edge therealong.

3. A straight edge for use in conjunction with a large drafting board, said straight edge consisting of `a bar of light density material, a yoke-shaped member, a clamping plate for securing said yoke member to said straight edge at one end thereof, a plunger member mounted for sliding movement to the opposite end of said straight edge yaxially thereof, a yoke member secured against movement to said plunger member, a pair of metallic bars, a clamping plate, means for collectively securing the last mentioned plate, said bars and the straight edge to the opposite end thereof, bearing means interposed between said plunger member and said bars in said pair for facilitating the movement of said plunger member, means carried by each of said bars extending laterally therefrom serving as stops for limiting the movement of said bearing means upon the sliding operation of said plunger member, a roller member mounted at the end of each arm of the rst and second mentioned yoke members for facilitating the movement of the straight edge along parallelly disposed elements of the drafting board, and a tension spring having one of its ends attached to means secured to the second mentioned clamping plate and its other end attached to means carried by said plunger member for urging said yoke members against the parallelly disposed elements of the drafting board.

References Cited by the Examiner UNITED STATES PATENTS 842,144 1/07 Gee 3380 975,956 11/10 Iwanami 33-80 1,145,922 7/ 15 Rigaumont. 2,047,868 7/36 Harley 308-6 2,243,838 6/41 Cunningham 33-76 2,854,751 10/58 Casey 33-80 FOREIGN PATENTS 21,329 9/09 Great Britain. 171,747 9/ 34 Switzerland.

ISAAC LISANN, Prinmry Examiner.

ROBERT B. HULL, Examiner. 

3. A STRAIGHT EDGE FOR USE IN CONJUNCTION WITH A LARGE DRAFTING BOARD, SAID STRAIGHT EDGE CONSISTING OF A BAR OF LIGHT DENSITY MATERIAL, A YOKE-SHAPED MEMBER, A CLAMPING PLATE FOR SECURING SAID YOKE MEMBER TO SAID STRAIGHT EDGE AT ONE END THEREOF, A PLUNGER MEMBER MOUNTED FOR SLIDING MOVEMENT TO THE OPPOSITE END OF SAID STRAIGHT EDGE AXIALLY THEREOF, A YOKE MEMBER SECURED AGAINST MOVEMENT TO SAID PLUNGER MEMBER, A PAIR OF METALLIC BARS, A CLAMPING PLATE, MEANS FOR COLLECTIVELY SECURING THE LAST MENTIONED PLATE, SAID BARS AND THE STRAIGHT EDGE OF THE OPPOSITE END THEREOF, BEARING MEANS INTERPOSED BETWEEN SAID PLUNGER MEMBER AND SAID BARS IN SAID PAIR FOR FACILITATING THE MOVEMENT OF SAID PLUNGER MEMBER, MEANS CARRIED BY EACH OF SAID BARS EXTENDING LATERALLY THEREFROM SERVING AS STOPS FOR LIMITING THE MOVEMENT OF SAID BEARING MEANS UPON THE SLIDING OPERATION OF SAID PLUNGER MEMBER, A ROLLER MEMBER MOUNTED AT THE END OF EACH ARM OF THE FIRST AND SECOND MENTIONED YOKE MEMBERS FOR FACILITATING THE MOVEMENT OF THE STRAIGHT EDGE ALONG PARALLELLY DISPOED ELEMENTS OF THE DRAFTING BOARD, AND A TENSION SPRING HAVING ONE OF ITS ENDS ATTACHED TO MEANS SECURED TO THE SECOND MENTIONED CLAMPING PLATE AND ITS OTHER END ATTACHED TO MEANS CARRIED BY SAID PLUNGER MEMBER FOR URGING SAID YOKE MEMBERS AGAINST THE PARALLELLY DISPOSED ELEMENTS OF THE DRAFTING BOARD. 